Thrust Reverser Actuation Systems (TRAS) power and control the deployment of aircraft thrust reversers. Thrust reversal, also called reverse thrust, involves the temporary diversion of a jet aircraft's exhaust so that it acts against the forward travel of the aircraft, providing deceleration, for example, to help slow an aircraft after touch-down. Such devices are considered important for safe operations by airlines.
However, such devices can also negatively affect the operation of an aircraft if they are misused or malfunction. A number of aircraft accidents have been traced back to accidental TRAS deployments. As such, many TRAS designs include mechanisms to control the deployment and stow speeds so that the TRAS is moved safely from one position to another during operation.